The trouble begins when one attempts to speak of tools used for interdisciplinary assembly. While chemists are able to assemble molecules using standard containers, the structures assembled are far from being considered nanomachines. Biological systems, on the other hand are clearly nanomechanical in nature, but we still have yet to reproduce such miraculous assembly synthetically. Thus, nanotechnology naturally involves the pursuit of a device that will allow us to assemble synthetic nanoscale devices of comparable molecular precision. It seems natural that such a device should be called an assembler.

The term assembler has been previously defined as "a molecular machine that can be programmed to build virtually any molecular structure or device from simpler chemical building blocks." This definition seems fundamentally flawed since the requirement for the tool itself to be a molecular machine is clearly unecessary. For instance, an automobile factory need not resemble the automobile that it assembles. I immagine useful assemblers could be created with existing lithographic methods. Indeed, the term "lab-on-a-chip" is used to refer to miniaturized tools for chemical analysis. However, the miniaturization and integration of chemical devices for the purpose of assembling atomically precise devices has yet to be developed. For instance, microfluidic devices might be used to carefully mix small volumes of fluids (ideally containing a discrete amount of components) while simultaneously observing and controlling the assembly process via feedback loops from single-assembly detectors.

Since the word assembler seemed to have been taken already, in a previous article I defined such a device as a self-assembler. However, I subsequently learned that the term self-assembler had been previously defined as an even more unnecessary device that would assemble copies of itself or self-replicate. So, in an attempt to provide more useful terminology for those who may wish to communicate about assembly, I have redefined the term assembler as, "a chemical device that given certain elemental or molecular inputs (starting materials) can output a specific molecular structure or aggregation." I have also redefined self-assembler and introduced a new term, directed assembler. According to these new definitions, assemblers exist today in the primitive form of a simple container (e.g. with precipitation being a typical form of self-assembly and electrochemistry being a typical form of directed assembly). However, miniaturizing, automating and improving the feedback controls of these chemical devices seems to be the most promising approach towards the development of a molecular nanotechnology.